I don't often start a book and not finish. The only one I can think of immediately is Grapes of Wrath which I have started three times, and have not made it past the first hundred pages.
I thought that I should read Jack Kerouac's On the Road, so when I saw the Library of America edition sitting in the new book area of the Library, I picked it up. I started reading it. It was quite a drag. It is billed as a novel, but with the first person narrative, and what appears to be a real story, I just don't get it. Late last year I read the memoirs of Jack's wife Edie Kerouac-Parker. It was not a bad read (even if not terribly well written). I had a very hard time with Jack's book.